JavaScript - Set.forEach() Method

The Set.forEach() method in JavaScript accepts a callback function as a parameter and executes it once for each element in the set, in insertion order.

Syntax

Following is the syntax of JavaScript Set.forEach() method −

forEach(callbackFn, thisArg)

Parameters

This method accepts only two parameters. The same is described below −

callbackFn − This is the function to execute for each element in the set, and it takes three parameters:
- value − The current element being processed.
- key − Key of each iteration. This is always the same as value.
- set − The set being iterated.
thisArg (optional) − Value to use as this when executing the callback.

Return value

This method returns none (undefined).

Examples of JavaScript Set.forEach() Method

Following are demonstrates the basic usage of Set.forEach() method −

Example 1

In the following example, we are using the JavaScript Set.forEach() method to iterate through each element in the "mySet" Set and prints them −

<html>
<body>
   <script>
      const mySet = new Set([1, 2, 3, 4]);
      mySet.forEach((value) => {
         document.write(value);
      });
   </script>
</body>
</html>

After executing the program, we can see that all the elements present in the set got printed.

Example 2

Here, the forEach() method iterates over elements in "mySet" set, and for each element, it multiplies it by 2, and stores the result in a new set named "newArray" −

<html>
<body>
   <script>
      const mySet = new Set([1, 2, 3]);
      const newArray = new Set();

      mySet.forEach((value) => {
         newArray.add(value * 2);
      });
      const resultArray = Array.from(newArray);
      document.write(resultArray);
   </script>
</body>
</html>

If we execute the program, we can see that all the elements got multiplied by 2 and stored in a new set.